March 21, 2005

Hoist By One's Own Petard

I knew the figurative meaning of this - to be done in through your own design or caught in a trap of your own making - but not the literal meaning. For some reason I thought a petard was a sword, but then I couldn't work out how "hoist" figured in. To lift oneself by one's sword? Huh? I think in my mind I must have mixed up the expression with to fall on the sword, which has more to do with sacrificing oneself for the sake of others. I guess the modern equivalent would be to take a bullet for someone.

Turns out a petard is a medieval-era incendiary device - a bomb. So to be hoisted by one's own petard is to be thrown, or lifted, by one's own bomb - to be blown up. Note that the name for this device comes from the French and also refers to a different sort of explosion: "a loud discharge of intestinal gas."

Falling on one's sword is a messy business, but there's a sense of nobility. In a way, it relates to that samurai business of hara-kiri.

To be hoist by one's own petard, however, aptly captures the lack of dignity and pain that is inherent in being stuck in a mess of one's own making.